Pump for conveying a viscous medium

ABSTRACT

A pump for conveying a viscous medium, comprising a feed hose in the pump housing, a support wall extending along the feed hose and supporting the feed hose in the housing, pressure rolls mounted for movement along the feed hose diametrically opposite the support wall and arranged to compress the feed hose between the support wall and a respective pressure roll as the pressure roll moves along the feed hose whereby the feed hose is successively deformed from a normal, expanded shape to a compressed, flattened shape and the viscous medium therein is conveyed from a suction to the output end of the feed hose, and a centering device engaging the feed hose at its periphery for holding the feed hose in alignment with the support wall and for returning the feed hose from the compressed to the normal shape after the pressure roll has passed, the centering device including resiliently yielding support elements mounted in the housing and arranged at both sides of the feed hose, the support wall and the pressure roll diametrically opposed to each other and exerting a radial thrust against the feed hose in a plane defined by the feed hose in the compressed, flattened shape, the support elements being yieldingly retracted by the flattened feed hose as it is compressed by the passing pressure roll into the flattened shape.

The present invention relates to a pump for conveying a viscous medium,such as concrete or mortar mixtures, which comprises a housing, a feedhose in the housing for conveying the viscous medium from a suction endthereof to an output end, a support wall extending along the feed hoseand suppoting the feed hose in the housing between the ends thereof,pressure rolls mounted for movement along the feed hose diametricallyopposite the support wall and arranged to compress the feed hose betweenthe support wall and a respective pressure roll as the pressure rollmoves along the feed hose whereby the feed hose is successively deformedfrom a normal, expanded shape to a compressed, flattened shape and theviscous medium therein is conveyed from a suction to the output end ofthe feed hose, and a centering device engaging the feed hose at itsperiphery for holding the feed hose in alignment with the support walland for returning the feed hose from the comprssed to the normal shapeafter the pressure roll has passed.

A pump of this type has been disclosed in German Pat. No. 1,203,137.This pump comprises a cylindrical housing having a suction end and anoutput end. A rotor in the housing carries a plurality of equidistantlyspaced pressure rolls for compressing the feed hose against the wall ofthe housing which serves as a suppot wall for the feed hose. Twodiametrically opposite support rollers are arranged in the direction ofrotation of the rotor behind the pressure rolls, the spacing between thesupport rollers corresponding to the diameter of the feed hose. Thesesupport rollers serve the purpose of returning the feed hose which hasjust been compressed by a pressure roll into a flattened shape to itsnormal, expanded shape. Considering the fact that the rotors of suchpumps operate at about 60 rpm and that the feed hoses have a very slowconveying motion, this structure does not assure that the supportrollers spaced a very short distance behind the pressure rolls willactually engage the sides of the flattened feed hose but, more often,will damage the feed hose and tear it at its sides. This happens, inparticular, because the feed hose is almost inert after it has beencompressed because of the prevailing vacuum therein and, therefore,expands only very slowly. It is another disadvantage of this structurethat the feed hose is not readily accessible for repairs or replacement.

It is a primary object of this invention to avoid the indicateddisadvantages in a pump of the first-described type and to obtain asatisfactory feeding velocity while protecting the feed hose againstdamage.

The above and other objects are accomplished according to the inventionwith a centering device which includes resiliently yielding supportelements mounted in the housing and arranged at both sides of the feedhose, the support wall and the pressure roll diametrically opposed toeach other and exerting a radial thrust against the feed hose in a planedefined by the feed hose in the compressed, flattened shape, the supportelements being yieldingly retracted by the flattened feed hose as it iscompressed by the passing pressure roll into the flattened shape.

Such support elements can be so constructed that they properly engagethe feedhose in its flattened shape to restore it to the expanded shapeafter it has been compressed by the passing pressure roll, independentlyof the velocity with which the pressure rolls move along the feed hose.This has the advantage that the feed hose is dependenly restored to itscylindrical shape without damage thereto. The restoring force of thesupport elements is generated by the force stored therein when they areresiliently retracted by the flattened feed hose as it is compressed bythe passing pressure roll into the flattened shape.

The above and other objects, advantages and features of the presentinvention will become more apparent from the following detaileddescription of certain now preferred embodiments thereof, taken inconjunction with the accompanying, somewhat schematic drawing wherein

FIG. 1 is a top view showing the feed hose, the support wall, thepressure roll and the centering device in cooperation according to thisinvention;

FIGS. 2 and 3 are end views of the embodiment of FIG. 1, FIG. 2 showingthe feed hose in its normal, expanded shape and FIG. 3 showing the feedhose in its compressed, flattened shape;

FIGS. 4 and 5 are, respectively, side and end views of the supportelements of the embodiment of FIG. 1.

Referring now to the drawing there is shown a pump for conveying aviscous medium, such as a concrete mixture or mortar. The pump compriseshousing 32 and rectilinearly extending feed hose 30 in support wall 31arranged on bottom wall 37 of pump housing 32 extends along feed hose 30and supports the feed hose in the housing between the ends thereof.Clamps 33 affix the suction and output ends of the feed hose to the pumphousing, and one of the clamps also mounts the feed hose output end onsteel pipe 34 which conveys the pumped viscous medium to a desiredlocation. Resiliently yielding support elements 35 are arranged at bothsides of feed hose 30, support wall 31 and pressure roll 40diametrically opposed to each other. As shown in FIG. 1, they extendalong the entire length of feed hose 30 for engagement therewith and areglidable in a direction parallel to axis 39 of the pressure rollsbetween bottom wall 37 and top plates 38 which form a guideway forglidable support elements 35. Diametrically oppositely arrangedpneumatic hoses 46, 46 extend parallel to feed hose 30 and resilientlyexert a radial thrust on the support elements to bias them towards thefeed hose. The pneumatic hoses are mounted in the guideways formed bybottom wall 37 and top plates 38 adjacent side walls 45 of pump housing32. The pneumatic hoses are interconnected at one of their ends by pipe48 while valve 47 is mounted at an opposite end of one of the pneumatichoses for supplying air under pressure to the pneumatic hoses. Ifsupport elements 35 have a length substantially corresponding to thediameter of feed hose 30 and a width substantially corresponding to theradius of the feed hose, the centering device may be readily adapted toany type of compressed feed hose shape while adequate engagement of thesupport elements with the periphery of the feed hose is assured andthere is a minimum of friction between the gliding support elements toavoid jamming.

As best shown in FIGS. 4 and 5, support elements 35 are parallelepipedand comprise domed support face 41 arranged for engaging the feed hoseand opposite domed pressure face 42 receiving pressure biasing thesupport elements toward feed hose 30, the parallelepiped supportelements consisting of two parallel sliding faces 36, 36 extending onthe direction of axes 39 of pressure rolls 40 and the domed support andpressure faces 41, 42 connecting the sliding faces. Curving supportfaces 41 so that they present a convex engagement face with the feedhose avoids sharp-edged engagements with the feed hose and improvedconformity to the compressed profile of the feed hose. In addition, thedomes shaped of the pressure faces of the support elements assures thatthey engage the feed hose along their longitudinal center line, thuspreventing jamming between the adjacent support elements and reducingfriction therebetween as they are resiliently pressed against the feedhose. Also, such ring-shaped support elements are light and, therefore,are displaceable resiliently with little force.

As shown in FIG. 4, the lower portions of sliding faces 36 and supportface 41 adjacent thereto define recess 43 in support element 35 and therecess has abutment 44 engaging support wall 31 (see FIGS. 2 and 3) forfeed hose 30. In the position of pressure roll 40 shown in FIG. 2,abutments 44 of support elements 35 engage support wall 31 under theradial thrust exerted upon the support elements by pneumatic hoses 46while leaving feed hose 30 in its normal, expanded shape. In thismanner, the feed hose remains centered on support wall 31 and remains inits cylindrical shape without being subjected to stress. Abutments 44accurately limit the displacement path of the support elements under theradial thrust of pneumatic hoses 46 to assure the centering of the feedhose. Furthermore, the support elements are held thereby under tensionin their foremost positions, which is adjustable for different operatingparameters dependent primarily on the type of viscous medium beingconveyed in the feed hose. When pressure roll 40 compresses feed hose 30containing a viscous medium to assume a flattened shape 49 (see FIGS. 1and 3), adjacent support elements will be automatically retracted andtheir pressure faces 42 will deform pneumatic hoses 46.

Since feed hose 30 glides up and down along pressure faces 41 of supportelements 35 as it assumes flattened shape 49 and is then returned to itsexpanded shape as pressure roll 40 moves on, it will be useful to applyFrench chalk or any other suitable lubricant to reduce friction betweenthe feed hose and the support elements. While the feed hose has beenillustrated as extending in a flat plane, it could also be arranged inan arc and could be compressed by a pressure roll mounted on a rotor. Ifthe feed hose extends arcuately, the support elements must be conicallyshaped in conformity to the curvature of the arc.

What we claim is:
 1. A pump for conveying a viscous medium,comprising(a) a housing, (b) a rectilinearly extending feed hose in thehousing for conveying the viscous medium from a suction end thereof toan output end, (c) a support wall extending along the feed hose andsupporting the feed hose in the housing between the ends thereof, (d)pressure rolls mounted for movement along the feed hose diametricallyopposite the support wall and arranged to compress the feed hose betweenthe support wall and a respective one of the pressure rolls as thepressure roll moves along the feed hose whereby the feed hose issuccessively deformed from a normal, expanded shape to a compressed,flattened shape and the viscous medium therein is conveyed from thesuction to the output end, and (e) a centering device engaging the feedhose at its periphery for holding the feed hose in alignment with thesupport wall and for returning the feed hose from the compressed to thenormal shape after the pressure roll has passed, the centering deviceincluding(1) a multiplicity of adjacent resiliently yielding,parallelepiped support elements mounted in the housing and arranged atboth sides of the feed hose, said support elements extending along theentire length of the feed hose for engagement therewith and comprising asupport face arranged for engaging the feed hose and an oppositepressure face receiving pressure biasing the support elements towardsthe feed hose, the support and pressure faces of the support elementsbeing domed, the support elements being glidable in a direction parallelto the axes of the pressure rolls and being biased towards the feedhose, the support wall and the pressure roll being diametrically opposedto each other and exerting a radial thrust against the feed hose in aplane defined by the feed hose in the compressed, flattened shape, andthe support elements being yieldingly retracted by the flattened feedhose as it is compressed by the passing pressure roll into the flattenedshape.
 2. The pump of claim 1, wherein the support elements arecomprised of synthetic resin.
 3. The pump of claim 1, further comprisingdiametrically oppositely arranged pneumatic hoses extending parallel tothe feed hose, the pneumatic hoses resiliently exerting the radialthrust on the support elements.
 4. The pump of claim 1, wherein thesupport elements have a length substantially corresponding to thediameter of the feed hose and a width substantially corresponding to theradius of the feed hose.
 5. The pump of claim 1, wherein theparallelepiped support elements consist of two parallel sliding facesextending in the direction of the pressure roll axes and the domedsupport and pressure faces connecting the sliding faces.
 6. The pump ofclaim 5, wherein lower portions of the sliding faces and the supportface adjacent thereto define recesses in the support elements and therecesses have an abutment engaging the support wall for the feed hose.